Abstract: 【Abstract】 Objective To investigate the clinical characteristics of cutaneous adverse reactions induced by programmed death-1 （PD-1） inhibitors. Methods It was a retrospective case series study analyzing the clinical data of hospitalized patients who developed cutaneous adverse reactions after treatment with PD-1 inhibitors at Wuhan No.1 Hospital between January 2020 and June 2023. Data collected included rash characteristics, relevant investigations, treatments, and follow-up outcomes. Results A total of 18 patients were included, comprising 11 males and 7 females; 12 patients （66.7%） were older than 60 years. Among different treatment regimens, cutaneous adverse reactions occurred more frequently in patients receiving PD-1 inhibitor monotherapy （10 cases） than in those receiving combination therapy （6 cases） or sequential therapy （2 cases）. PD-1 inhibitor-associated cutaneous eruptions were heterogeneous, most commonly presenting as eczema and nonspecific maculopapular rashes accompanied by refractory pruritus; the most severe manifestation was bullous pemphigoid-like lesion. In 14 patients （77.8%）, the skin eruptions were effectively controlled after the addition of systemic glucocorticoids. Among them, 12 patients （85.7%） received low-to-moderate doses of glucocorticoids. Five patients showed poor control of skin lesions with systemic glucocorticoids therapy alone and required combination treatment with immunosuppressive agents （cyclophosphamide, cyclosporine, mycophenolate mofetil, or methotrexate）; 1 patient also received dupilumab, with no evidence of tumor progression. Patients receiving combination or sequential therapy had a longer duration of first hospitalization. During follow-up, 2 patients were lost to follow-up, 3 died, 7 patients （53.8%） achieved complete resolution of skin eruptions, and 11 patients （84.6%） had stable tumor disease. PD-1 inhibitor therapy was temporarily discontinued in 9 patients, while 4 patients continued treatment with the original PD-1 inhibitor. Conclusions Cutaneous adverse reactions are common during PD-1 inhibitor therapy and occur more frequently with monotherapy; however, severe cutaneous adverse reactions are most often observed in patients receiving combination or sequential treatment. PD-1 inhibitor-associated skin eruptions are heterogeneous and characteristic, and most cases require the addition of systemic glucocorticoids for effective management.

Key words: Immune checkpoint inhibitors, Drug-related side effects and adverse reactions, Drug eruptions, Therapy, Glucocorticoids